Publicação
Potential of bioenergy in transportation systems from endogenous resources in Ecuador
| Resumo: | Climate change is a serious threat to sustainability. Anthropogenic climate change is due to the accumulation of greenhouse gases (GHG) in the atmosphere beyond natural levels. Globally, the transportation sector contributes to 14% of the overall GHG emissions; road transportation corresponds to two-thirds of this percentage. The road transportation sector in Ecuador is characterized by its primary use of fossil fuels as a source of energy. In 2016, this sector emitted 18.5 million tonnes of GHG, corresponding to 42% of the emissions of all sectors. Given this context, it is imperative to decarbonize road transportation by inserting alternative energy carriers and powertrain technologies. Electrification and use of biofuels on light-duty vehicles and mass transportation fleets are considered opportunities for GHG emissions mitigation and for improving local air quality. The electricity generation mix in Ecuador is mainly derived from hydropower, hence incurs relatively low GHG emissions along its life cycle. In this research, the insertion of electric and hybrid vehicles operated with alternative fuels in Ecuadorian road transportation is analyzed from an environmental perspective, using two well-known methods: Life cycle assessment (LCA) and well-to-wheels analysis (WTW). Results indicate that mitigation of GHG is possible when conventional buses used on bus rapid transit (BRT) systems are replaced by electric buses, considering an electricity generation mix of low and high hydropower. However, for a marginal electricity scenario, an inverse behavior is evidenced; the GHG emissions increased by 1 kilotonne for each 25% increase of electric bus penetration. On the other hand, if Ecuador decides to hybridize the public bus fleet, using ethanol as a fuel source, the country will need a production of approximately 1300 million liters of ethanol to satisfy the final energy demand. In terms of GHG emissions, there would be a considerable mitigation of CO2 emissions (almost 80%) during the operational phase, when conventional fleet buses are replaced with plug-in hybrid buses. However, this is an enormous challenge for a country that only produces 50-60 million liters of ethanol per year. In terms of light-duty passenger vehicles, the environmental performance of a battery electric vehicle and ethanol-gasoline blend flex-fuel vehicle were analyzed by means of an attributional LCA for current and future scenarios. The results for current scenarios show that light-duty vehicles using ethanol-gasoline blends have higher environmental impacts than battery electric vehicles for global warming potential (GWP-130-180 g CO2-eq/km for E5 (gasoline additivated with 5% of ethanol) and 42–176 g CO2-eq/km for BEVs.), fossil depletion potential (FDP), marine eutrophization potential (MEUP), ozone depletion potential (ODP), particulate matter formation potential (PMFP), photochemical oxidant formation potential (POFP), and terrestrial acidification potential (TAP) categories. In contrast, using the current electricity mix, the battery-electric vehicle has higher environmental impacts in freshwater eutrophization (FEP) and metal depletion (MDP) categories. In general, a battery electric vehicle has a better environmental performance than flex-fuel when in fact the electricity generated to charge such vehicles is highly renewable. The more fossil fuel electricity is used the flex-fuel vehicles will perform environmentally better. Nevertheless, E85 flex-fuel vehicles should not be discarded if the electricity generation for battery electric vehicles is not highly green (renewable or biobased). The Ecuadorian government needs policies that promote advanced transportation technologies, including alternative vehicles and energy carriers such as electricity or biofuels on transportation systems. Moreover, Ecuador should have policies and technical instruments to avoid charging electric vehicles with marginal fossil electricity. |
|---|---|
| Autores principais: | BASTIDAS, DANILO ANDRES ARCENTALES |
| Assunto: | autocarros híbridos plug-in perspectiva do ciclo de vida análise do poço às rodas mitigação de emissões desempenho ambiental plug-in hybrid buses life cycle perspective well-to-wheels analysis emission mitigation environmental performance |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Climate change is a serious threat to sustainability. Anthropogenic climate change is due to the accumulation of greenhouse gases (GHG) in the atmosphere beyond natural levels. Globally, the transportation sector contributes to 14% of the overall GHG emissions; road transportation corresponds to two-thirds of this percentage. The road transportation sector in Ecuador is characterized by its primary use of fossil fuels as a source of energy. In 2016, this sector emitted 18.5 million tonnes of GHG, corresponding to 42% of the emissions of all sectors. Given this context, it is imperative to decarbonize road transportation by inserting alternative energy carriers and powertrain technologies. Electrification and use of biofuels on light-duty vehicles and mass transportation fleets are considered opportunities for GHG emissions mitigation and for improving local air quality. The electricity generation mix in Ecuador is mainly derived from hydropower, hence incurs relatively low GHG emissions along its life cycle. In this research, the insertion of electric and hybrid vehicles operated with alternative fuels in Ecuadorian road transportation is analyzed from an environmental perspective, using two well-known methods: Life cycle assessment (LCA) and well-to-wheels analysis (WTW). Results indicate that mitigation of GHG is possible when conventional buses used on bus rapid transit (BRT) systems are replaced by electric buses, considering an electricity generation mix of low and high hydropower. However, for a marginal electricity scenario, an inverse behavior is evidenced; the GHG emissions increased by 1 kilotonne for each 25% increase of electric bus penetration. On the other hand, if Ecuador decides to hybridize the public bus fleet, using ethanol as a fuel source, the country will need a production of approximately 1300 million liters of ethanol to satisfy the final energy demand. In terms of GHG emissions, there would be a considerable mitigation of CO2 emissions (almost 80%) during the operational phase, when conventional fleet buses are replaced with plug-in hybrid buses. However, this is an enormous challenge for a country that only produces 50-60 million liters of ethanol per year. In terms of light-duty passenger vehicles, the environmental performance of a battery electric vehicle and ethanol-gasoline blend flex-fuel vehicle were analyzed by means of an attributional LCA for current and future scenarios. The results for current scenarios show that light-duty vehicles using ethanol-gasoline blends have higher environmental impacts than battery electric vehicles for global warming potential (GWP-130-180 g CO2-eq/km for E5 (gasoline additivated with 5% of ethanol) and 42–176 g CO2-eq/km for BEVs.), fossil depletion potential (FDP), marine eutrophization potential (MEUP), ozone depletion potential (ODP), particulate matter formation potential (PMFP), photochemical oxidant formation potential (POFP), and terrestrial acidification potential (TAP) categories. In contrast, using the current electricity mix, the battery-electric vehicle has higher environmental impacts in freshwater eutrophization (FEP) and metal depletion (MDP) categories. In general, a battery electric vehicle has a better environmental performance than flex-fuel when in fact the electricity generated to charge such vehicles is highly renewable. The more fossil fuel electricity is used the flex-fuel vehicles will perform environmentally better. Nevertheless, E85 flex-fuel vehicles should not be discarded if the electricity generation for battery electric vehicles is not highly green (renewable or biobased). The Ecuadorian government needs policies that promote advanced transportation technologies, including alternative vehicles and energy carriers such as electricity or biofuels on transportation systems. Moreover, Ecuador should have policies and technical instruments to avoid charging electric vehicles with marginal fossil electricity. |
|---|